For future reference, the plumber I have phoned is DT Hunt, who examination of the faded business cards on the pinboard suggests we have phoned before. Sadly, I cannot remember him or whether he did a decent job, but I'm gambling that Past Us would not have kept the phone number if he'd been a complete whittle. I seem to have a plumbing tag in which I have recorded various leaks, but not actually useful information such as who did the fixing...
Update : alas, Mr Hunt was abroken reed and did not return the call. I called Mr Utton instead, who turned out to be someone we'd called before, and very efficient he seemed, though he needs to call to arrange to return, and has yet to do so.

Comments
Hold on and good luck!
washer stops working
call service plan
service plan schedules for the Monday a week and a half ahead
service guy shows up
service guy says it's either a motor or a sensor
service center does not have parts (washer is only about 11 years old, what? same motor that they're putting into the new ones!)
service guy orders parts
parts show up
we reschedule service call--another week ahead
service guy never shows up
reschedule call AGAIN, for yesterday
service guy shows up
service guy fixes washer, says washer is going to die soon
today is a month from the day I texted my husband "Confirmed, the washer is bollocked."